The present invention relates to the treatment and recycling of waste material, especially waste material having a high liquid content. More particularly, the invention is directed to an apparatus for recovering liquid from refuse liquid-filled containers.
In the food industry, millions of dollars are wasted annually by discarding refuse containers filled with liquid food products, such as milk, cream or fruit juice, due to overdating (i.e. the expiry date of the food product has passed), batching error (e.g. wrong percentage of fat in milk having a predetermined fat content) and/or error in the volume of content or container. Attempts have been made to puncture or shred refuse milk cartons with a view to recovering the milk therefrom. However, the puncturing or shredding of milk cartons produces small cardboard fragments which contaminate the milk, thus rendering it unsuitable for human consumption.
Various pressing apparatuses are known in the art for separating liquid from solid matter. For example, U.S. Pat. No. 4,343,233 describes an apparatus for producing and collecting a liquid extract and a pressed dry by-product from a mash of fibrous material, which includes an extraction chamber and a mechanism for compressing the mash of fibrous material within the extraction chamber to extract the liquid and from a pressed dry product therefrom. In one of the embodiments disclosed in this patent, the means for compressing the mash includes two diametrically opposed fluid motors each having a plunger which is insertable within opposite ends of the extraction chamber and movable in opposed directions within the chamber to compress the mash, thereby extracting the liquid therefrom which passes through collecting openings located in the chamber and producing a pressed dry by-product. The pressed dry by-product is expelled from the extraction chamber by withdrawing one of the plungers from the extraction chamber and extending the other plunger to the end of the chamber, thereby discharging the by-product from the chamber.
U.S. Pat. No. 4,303,412 discloses a similar type of pressing apparatus for separating waste material into a liquid or semisolid sludge and a solid waste, wherein use is made of a piston arrangement designed to mass of waste. Virtually all liquid, semisolid or viscous material can thus be extracted from the waste to obtain sludge useful in agriculture.
Although such prior art presses are suitable for separating refuse into a liquid, on the one hand, and solids substantially devoid of moisture, on the other hand, they are not capable of separating large quantities of liquid such as contained in refuse milk cartons or bags, where the liquid represents more than 95% by volume of the refuse, due to the hydrostatic pressure exerted by the liquid.